* {
    padding: 0;
    margin: 0;
}

li {
    list-style: none;
}

.banner {
    width: 400px;
    height: 300px;
    margin: auto;
    position: relative;
}

.banner ul li {
    width: 400px;
    height: 300px;
    text-align: center;
    line-height: 300px;
    font-size: 50px;
    position: absolute;
    top: 0;
    background-color: #f00;

    opacity: 0;
    transition: .5s;
}
.banner ul img {
    width: 100%;
    height: 100%;
}

.banner span {
    width: 30px;
    height: 30px;
    text-align: center;
    line-height: 30px;
    background-color: #000;
    color: #fff;
    position: absolute;
    top: 0;
    bottom: 0;
    margin: auto;
}

.banner .next {
    right: 0;
}

.banner ol {
    position: absolute;
    width: 100%;
    bottom: 10px;
    display: flex;
    justify-content: center;
}

.banner ol li {
    width: 20px;
    height: 20px;
    background-color: #ff0;
    margin: 10px;
}

.banner .show{
    opacity: 1;
}
.banner .active{
    background-color: #0f0;
}